Help needed :)

[nikmak]

Hope this is in the right place!

Here goes; I have acquired a set of Bang & Olufsen BEOVOX 5702 speakers as part of a job lot at auction. Was bidding on the other item and didn't really know much about these speakers. I instantly stuck them for sale on gumtree and got a couple of hits straight away requesting details on the condition. I opened them up and the bass cones were rotted away. On opening I obviously found out they have the Celestion HF2000 and the MD500 tweeters inside.

I am guessing the owner of these originally was a serious collector as the reel2reel I got was in mint condition and the exterior of these cabs isn't too bad. So well looked after.

I have taken these out with the view to getting rid of them on ebay but need to test them. (I have a multimeter) I am a little unsure of what I am doing though. So any advice or what to look out for is appreciated. I did try already but got less than 8ohms on the HF2000's and around 9 ohms on the MD500s. This is presuming I am testing these correctly... :scratch:

On a different note, in my cupboard I have a ditton 25 and a ditton 44 (unpaired). Maybe I should just make a hybrid speaker out of the parts somehow? Or maybe get shot of the lot and reclaim the space! :mental::rolleyes:

Any words of wisdom gratefully received!

Cheers :)
P.S Also acquired was the 3702's

[walpurgis]

The 5702 is a very good speaker and well worth resurrecting if possible. They are a close relative of the Celestion Ditton 66. Your measurements for the drivers sound about right. What is wrong with the bass drivers exactly and are the passive ABRs OK? Do you have photos?

[nikmak]

The 5702 is a very good speaker and well worth resurrecting if possible. They are a close relative of the Celestion Ditton 66. Your measurements for the drivers sound about right. What is wrong with the bass drivers exactly and are the passive ABRs OK? Do you have photos?

The foam on the bass drivers has rotted away. I'm not sure what passive ABR'S are but Im guessing the other area beside the bass driver. That had also rotted away. Way beyond repair from what I can tell?

The HF tweeters measured about 7 ohms. Is that not odd if they are the 8 ohm tweeters.? I think I'll need to take them for someone else to test.

[struth]

yes, good drivers...youve got them wrong way round i think the 2000 is the tweeter; the other the mid... ohms check is good.. can certainly be fixedI guess if you can find new foam kit

[walpurgis]

The foam on the bass drivers has rotted away. I'm not sure what passive ABR'S are but Im guessing the other area beside the bass driver. That had also rotted away. Way beyond repair from what I can tell?

The HF tweeters measured about 7 ohms. Is that not odd if they are the 8 ohm tweeters.? I think I'll need to take them for someone else to test.

Any driver can be repaired or replaced. Cone surrounds are not really hard to replace. Spare parts for these speakers do appear on eBay.

The 8 ohm rating for drive units is the impedance, not the resistance. Impedance is calculated under dynamic conditions and is an average of the varying load confronting the amplifier. The average 8 ohm rated driver can have a resistance (not impedance) of anywhere between 4 ohms and 8 ohms. It depends on what the manufacturer deems right and this varies.

Some photos could be useful.

[nikmak]

http://postimg.org/image/ndb4cwsbh/

http://postimg.org/image/nuv2g1nn7/

http://postimg.org/image/nuv2g1nn7/

http://postimg.org/image/ndb4cwsbh/

The mesh for the tweeter was inside the speaker btw.

Cheers for the help so far. Every day is a school day!! :)

[Light Dependant Resistor]

Try to move away from foam as you can be sure it will perish again and again. Rubber is a good
much longer term material.

[walpurgis]

Looking at the pictures I can see that the dust cap on the Philips bass units has perished. These are easy and cheap to replace and available on eBay and the drive unit is likely to be OK otherwise. The lower unit with the rotted surround is a KEF BD139 passive radiator and can be replaced with later units with rubber surrounds that don't perish. These too are available from eBay (I've bought two pairs myself). I hope you have both MD500 midrange units.

The B&O 5702 is a serious monitor quality speaker and capable of excellent sound.

[nikmak]

Looking at the pictures I can see that the dust cap on the Philips bass units has perished. These are easy and cheap to replace and available on eBay and the drive unit is likely to be OK otherwise. The lower unit with the rotted surround is a KEF BD139 passive radiator and can be replaced with later units with rubber surrounds that don't perish. These too are available from eBay (I've bought two pairs myself). I hope you have both MD500 midrange units.

The B&O 5702 is a serious monitor quality speaker and capable of excellent sound.

Yes have both MD500 mid range units. I had started stripping everything out. Top advice, cheers.

If I was to replace the drivers and renovate the speakers, what do you suggest for the speaker connection terminals? They seem very dated? Better to leave as is or upgrade/modify?

[walpurgis]

Yes. Updated terminals would be good. Can you show a picture of yours? I can't recall what they were like on those speakers. It'll give me an idea of what modern replacement may suit.

You don't need to replace the Philips bass drivers, just replace the dustcaps! :)

You are in luck. There's a late pair of KEF BD139 units with rubber surrounds on eBay now at a sensible £29.99.

http://www.ebay.co.uk/itm/Pair-of-Kef-Passive-Radiators-Made-in-England-SP1042-/272097825493?hash=item3f5a4b52d5:g:oLMAAOSw3ydVibd o

They look slightly different, but will fit and work fine.

[walpurgis]

Note. The perforated cover on the HF2000 tweeters is good protection for the fragile domes and is also necessary for the correct performance of the unit. It is held in place with thin double sided adhesive tape, Which is why it falls off after about thirty years, once the adhesive ages and fails.

[nikmak]

Note. The perforated cover on the HF2000 tweeters is good protection for the fragile domes and is also necessary for the correct performance of the unit. It is held in place with thin double sided adhesive tape, Which is why it falls off after about thirty years, once the adhesive ages and fails.

Currently like this.

http://postimg.org/image/q71yopdx3/

Any particular adhesive tape I should use? Btw, thanks for that ebay link.

This was my main reason for bidding on the auction.... http://postimg.org/image/6rul99ts7/

All in all £20!!! So probably did ok! :)

[Arkless Electronics]

Around 5.6 Ohm is a good average for what you'll normally measure for an 8 Ohm unit. It can of course vary so I wouldn't worry so long as it's between 5.2 and 7.
When reading low ohms the meter will often add an ohm or two so it's best to check what you are getting for shorted meter probes. Plug/unplug leads a few times and give the selector switch on the meter a bit of exercise to get it lower ;)
Personally I would be tempted to leave the speaker connectors as standard for originality. If they are treated with contact cleaner and given a good checking out they shouldn't be any impediment to sound quality IMHO, a good connection's a good connection whether or not it's massive and gold plated.
These should be very good speakers when sorted! :) Oh yeah crossover caps if electrolytic may be due replacement by now for best results....

[walpurgis]

Can you even tell which wire is 'positive'? I'd definitely use a modern terminal set here. And maybe rewire with something decent. As Jez says, new capacitors (of suitable type) may benefit.

A pair of these terminal sets could do the trick at modest cost: http://www.ebay.co.uk/itm/Large-Speaker-Terminals-x2-/321824332227?hash=item4aee3999c3:g:3O8AAOSwEK9T5Ns v

You can of course spend more.

[nikmak]

Thanks Jez and Geoff. Ordered the KEF radiators today, so guess I'll be keeping them after all! Still need to buy dust caps, so any recommendations them would be helpful. I'll think about the terminals and capacitors at a later stage. Ultimately this is my first project so I'll keep it one stage at a time :)

Also, finally got round to having a look at the 3702's today and took the grills off and the foam has gone on the bass units. Any tips for replacement of those? Worth it? The cabinets are in absolutely pristine condition on these, shame it's not the other way about!

Cheers,Niki

[walpurgis]

Still need to buy dust caps, so any recommendations them would be helpful.

Measure the width where the old dustcaps were and order something of similar size.

I'm not saying these are the right size, but something like this: http://www.ebay.co.uk/itm/2-piece-54mm-PP-DUST-CAP-FOR-SUBWOOFER-BASS-SPEAKER-DOME-/252214840596?hash=item3ab92d0d14:g:uZ8AAOSwj0NUcpI K

They are from China, so you be waiting a few weeks, but the speakers are perfectly usable without.


You should find generic cone surrounds that will fit the 3702 speakers.


For glueing the caps or surrounds use a water based adhesive like Aleene's: http://www.ebay.co.uk/itm/Aleenes-Original-Tacky-Glue-4-fl-oz-118-ml-/201522262427?hash=item2eeba9b19b:g:iywAAOSwezVWvbe 7

It's what I use for speaker repairs.

[nikmak]

Yes. Updated terminals would be good. Can you show a picture of yours? I can't recall what they were like on those speakers. It'll give me an idea of what modern replacement may suit.

You don't need to replace the Philips bass drivers, just replace the dustcaps! :)

You are in luck. There's a late pair of KEF BD139 units with rubber surrounds on eBay now at a sensible £29.99.

http://www.ebay.co.uk/itm/Pair-of-Kef-Passive-Radiators-Made-in-England-SP1042-/272097825493?hash=item3f5a4b52d5:g:oLMAAOSw3ydVibd o

They look slightly different, but will fit and work fine.
Hi Back again. Getting round to starting this project and unpackaged the KEF radiators for the first time. I notice they are a different size from the original radiators. When you say they will fit fine, did you mean just use them as they are or strip the rubber out and renovate the original Beovox radiators? #confused!

[walpurgis]

The later BD139s have a different shaped frame edge, That's all, but the mounting holes are still in the same position. Use them as they are. They should bolt straight in. Do not strip them. They'll be ruined.

[nikmak]

The later BD139s have a different shaped frame edge, That's all, but the mounting holes are still in the same position. Use them as they are. They should bolt straight in. Do not strip them. They'll be ruined.

Thanks again :)

[nikmak]

Ok back again!

So, I still haven't finished this project. I've been planning to offload the speakers but haven't really had any bites so far so I think I am going to repair them properly. I bought the Kef BD139 and put them on to the speaker. This was an error as they just don't look right. I adapted some strong card(yes i know) to fill in the gaps left by the oval shaped 'kef b139 sp1037' radiators (originals) and it all looks a bit naff.

What I'd like to do now is repair my original oval 'B139 SP1037' Kef radiators and put them back on instead of the makeshift BD139. Can somebody put me in the right direction for doing this? Getting a replacement foam, getting the correct adhesive etc. I have a had a google search but didn't really come up with anything definitive.
Thanks!